From fb20a176ee18341cf01ece1496af1450d6c831fb Mon Sep 17 00:00:00 2001
From: Ben Fry <ben@fathom.info>
Date: Sun, 16 Jul 2023 12:40:21 -0400
Subject: [PATCH] fix pdf colors outside the range causing NPE (resolves #740)

---
 core/src/processing/awt/PGraphicsJava2D.java  | 61 +++++++++++--------
 .../pdf/src/processing/pdf/PGraphicsPDF.java  |  8 +++
 todo.txt                                      |  3 +-
 3 files changed, 44 insertions(+), 28 deletions(-)

diff --git a/core/src/processing/awt/PGraphicsJava2D.java b/core/src/processing/awt/PGraphicsJava2D.java
index ee41fe052..edb376710 100644
--- a/core/src/processing/awt/PGraphicsJava2D.java
+++ b/core/src/processing/awt/PGraphicsJava2D.java
@@ -2607,37 +2607,44 @@ public class PGraphicsJava2D extends PGraphics {
       clearPixels(backgroundColor);
 
     } else {
-      Color bgColor = new Color(backgroundColor);
-      // seems to fire an additional event that causes flickering,
-      // like an extra background erase on OS X
-//      if (canvas != null) {
-//        canvas.setBackground(bgColor);
-//      }
-      //new Exception().printStackTrace(System.out);
-      // in case people do transformations before background(),
-      // need to handle this with a push/reset/pop
-      Composite oldComposite = g2.getComposite();
-      g2.setComposite(defaultComposite);
-
-      pushMatrix();
-      resetMatrix();
-      g2.setColor(bgColor); //, backgroundAlpha));
-//      g2.fillRect(0, 0, width, height);
-      // On a hi-res display, image may be larger than width/height
-      if (image != null) {
-        // image will be null in subclasses (i.e. PDF)
-        g2.fillRect(0, 0, image.getWidth(null), image.getHeight(null));
-      } else {
-        // hope for the best if image is null
-        g2.fillRect(0, 0, width, height);
-      }
-      popMatrix();
-
-      g2.setComposite(oldComposite);
+      backgroundRect();
     }
   }
 
 
+  protected void backgroundRect() {
+    Color bgColor = new Color(backgroundColor);
+
+    // While more complete, this seems to fire an additional event that
+    // causes flickering, like an extra background erase on OS X.
+    //if (canvas != null) {
+    //  canvas.setBackground(bgColor);
+    //}
+
+    // If there are transformations or blending changes at the top of
+    // draw() (before background() is called) or still in place from
+    // the last trip through draw(), need to store and re-apply after.
+    Composite oldComposite = g2.getComposite();
+    g2.setComposite(defaultComposite);
+    pushMatrix();
+    resetMatrix();
+
+    g2.setColor(bgColor);
+    // On a hi-res display, image may be larger than width/height
+    if (image != null) {
+      // image will be null in subclasses (i.e. PDF)
+      g2.fillRect(0, 0, image.getWidth(null), image.getHeight(null));
+    } else {
+      // hope for the best if image is null
+      g2.fillRect(0, 0, width, height);
+    }
+
+    // Reset the drawing state (see above)
+    popMatrix();
+    g2.setComposite(oldComposite);
+  }
+
+
 
   //////////////////////////////////////////////////////////////
 
diff --git a/java/libraries/pdf/src/processing/pdf/PGraphicsPDF.java b/java/libraries/pdf/src/processing/pdf/PGraphicsPDF.java
index c0bb22f17..ea1574908 100644
--- a/java/libraries/pdf/src/processing/pdf/PGraphicsPDF.java
+++ b/java/libraries/pdf/src/processing/pdf/PGraphicsPDF.java
@@ -496,6 +496,14 @@ public class PGraphicsPDF extends PGraphicsJava2D {
   //////////////////////////////////////////////////////////////
 
 
+  public void backgroundImpl() {
+    // Override so that even with alpha, we draw a rectangle.
+    // https://github.com/processing/processing4/issues/740
+    backgroundRect();
+  }
+
+  //
+
   public void loadPixels() {
     nope("loadPixels");
   }
diff --git a/todo.txt b/todo.txt
index b31ad19cf..6f4e33cb0 100755
--- a/todo.txt
+++ b/todo.txt
@@ -1,5 +1,6 @@
 1293 (4.2.1)
-
+X `NullPointerException` when background exceeds color range when writing PDF
+X   https://github.com/processing/processing4/issues/740
 
 sampottinger
 X Syntax error highlighting placement / width incorrect